How can I estimate the CO₂ uptake of a plant?

Question

I would like to make an estimation of the CO₂ uptake of plants I cultivate, including, lettuce and aromatic herbs, such as thyme, basil, rosemary. What I want is to end up with a rough indicator for business purpose, not some super-accurate measurement.

1. Is there already average CO₂ uptake data per plant type available?
2. Will this uptake vary drastically per plant type?
3. Can I calculate the estimate through a simple measurement (e.g. of plant weight) or does it require tight lab experiments? In the former case, how is that measurement made?

Please bear in mind I'm not a scientist, but and end-user of science. Thank you for helping me this question if needed.

Answer 1

Can I calculate the estimate through a simple measurement (e.g. of plant weight) or does it require tight lab experiments? In the former case, how is that measurement made?

In the textbook Plant Physiological Ecology*, they state that about 40% of the dry weight of plants is carbon, and I believe the vast majority of that is from CO₂ from the atmosphere. You can take a fresh weight of an entire plant, and then dry it at the lowest temperature in your kitchen oven for a couple of days to get a reasonably accurate dry weight. That dry weight times 0.4 will give you an estimated total carbon, though I have seen other factors used. Plants can also be analyzed for Total Organic Carbon in some agricultural laboratories. Fast growing plants are going to absorb more carbon than slow growing ones.

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^{* Lambers, H, Thijs L. Pons, and F S. Chapin. Plant physiological ecology. New York: Springer Verlag, 2008. Print. ISBN:978-0-387-78341-3}